New Babolat technology can track various metrics, including where the ball hits the string bed.

Tennis players know all about the feel of hitting the sweet spot in the strings. Now they can back up that feeling with facts. The first tennis racquet with an on/off switch is also the first racquet to track stroke data, including where the ball hits the string bed.

The Babolat Play Pure Drive Set will launch on Dec. 12. Babolat, a French racquet manufacturer founded in 1875, revealed the racket to PopMech early, showing off the culmination of a 10-year project.

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CEO Eric Babolat envisioned the connected racket a decade ago, but it took time for sensor technology to shrink down and lighten up enough so that he wouldn't have to strap a backpack and wires to players. There's no need for bulky contraptions in Babolat Play. The smart version of the Pure Drive (the sport's top-selling racquet over the last 10 years) weighs the same 10.6 ounces as the analog version.

"There were two things in mind," Babolat says. "One is to enrich the tennis players' experience by having technology you don't feel or see and don't change your game because of [it]. And the second one is to enrich your play level. Whether Rafael Nadal or a beginner in a club, you have no info about what is happening when the ball hits the strings. We are bringing that for every tennis player."

Babolat teamed with French firm Movea, the company behind the Nintendo Wii remote, to build the digital guts. Inside the otherwise-hollow grip they placed an accelerometer and gyroscope along with a 6-hour battery, USB port, Bluetooth connectivity, and enough memory to hold 150 hours of play data.

Pierre Mace, R&D manager for the Babolat Play project, says tougher than loading the racquet with technology was establishing the right algorithms to accurately track the data coming through the sensors every time the racquet moves and hits a ball. "Our job was to change the signal into big things for the player," says Gael Moureaux, product manager.

The Babolat Play detects stroke type—forehand, backhand, smash, and first and second serves—measures spin and power, tracks rally length and play time, and maps out the location the ball strikes the string bed. The racquet saves all that data, which is available for download to an app via either Bluetooth to Android or Apple mobile devices, or USB to a computer. In two test sessions, the app distilled the information accurately.

To help the racquet to weed out all nonplaying movements, such as when a player uses it to scoop up a ball from the ground, or slams it against a bench, Babolat studied the information coming into the sensor and used actual common-sense playing data to help. How does the Babolat Play know it was a second serve instead of a first serve? The time elapsed between the two strokes plays into it. How does it know a stroke was a smash and not a serve? A smash always comes after another stroke type, while a serve starts a point. By understanding the game, the racquet makes sense of the player's movements. While developing the algorithm, engineers also compared high-speed video to the vibrations coming into the sensor. Now the system can tell—without placing any sensors on the strings—where the ball struck the string bed.

The app saves training and match sessions, shares information in a community setting, and compares data head-to-head with friends or top players—so you can see how well you stack up against a champion like Nadal. The International Tennis Federation has gotten on board with the Babolat Play too. It put into place tennis's 31st rule, which states that starting Jan. 1, 2014, players may record data during a match.

"The oldest company in tennis is making tennis cool," Eric Babolat says. All with an on/off switch.

Tim Newcomb covers sports and infrastructure for Popular Mechanics. Follow him on Twitter at @tdnewcomb.